Trinium, a valuable mineral, was discovered on PXY-887, where it is called "ke" by the native Salish. Though brittle as a raw ore because of its impurities, it is 100 times lighter and stronger than steel when forged. Unknown on Earth, it is the basis of several alien technologies, including the naquadah reactor and Tollan phase-shift technology. The SGC was unsuccessful in negotiating mining rights on PXY-887 but has since established an off-world trinium mine. The stargate's titanium iris was replaced by a stronger trinium-titanium alloy after it was destroyed by the gravity of the black hole, and a trinium alloy was also used in the construction of the Prometheus.
Cross Reference: Iris, PXY-887, Prometheus, Tollan Phase-Shift Technology, Tollans
Episode Reference: Spirits, Between Two Fires